During the last decade the development of various peptides amphiphiles [Cui et al., Peptide Science 94(1): 1-18 (2010)] and self-assembling molecules led to the preparation of nanostructures having different morphologies like one dimensional nanofibers, nanobelts, ribbons or helices [Palmer et al., Acc. Chem. Res. 41(12): 1674-1684 (2008)]. The growth and dimensions of these open one dimensional self-assembly often lack the control that can be found in closed systems like self-assembled nanocages [Tominaga et al., Angew. Chem. Int. Ed. 43(42): 5621-5625 (2004); Yoshizawa et al., Angew. Chem. Int. Ed. 48(19): 3418-3438 (2009)] or DNA based nanostructures [Lo et al., J. Am. Chem. Soc. 132(30): 10212-10214 (2010); Lo et al., Curr. Opin. Chem. Biol. 14(5): 597-607 (2010)].
Different approaches have been proposed to control the length of one-dimensional self-assembled objects. For example, one can control the supramolecular polymerization of monomers interacting with a template by hydrogen bonding by capping or a vernier approach [Ross Kelly et al., Tetrahedron Lett. 39(22): 3675-3678 (1998)]. Control of the nucleation and kinetics of growth have been particularly effective in the case of cylindrical micelles formed by crystalline block-copolymers [Wang et al., Science 317(5838): 644-647 (2007)], however as this method is based on the control of a supramolecular living polymerization, the nanostructures prepared using this methodology are still relatively polydisperse.
In 2008, a more versatile templating approach was proposed for the preparation of monodisperse self-assembled nanostructures [Bull et al., J. Am. Chem. Soc. 130(9): 2742-2743 (2008)]. This strategy was inspired by the self-assembly of helicoidal filamentous viruses like the TMV which is formed by the directed self-assembly of proteins (capsomers) on a RNA template [Klug, Philosophical Transactions: Biological Sciences 354(1383): 531-535 (1999)]. This bioinspired strategy involved specific interactions between a dumbbell-shaped template and the self-assembling peptide amphiphile. In aqueous solution, coassembly was favored by hydrophobic collapse resulting in the formation of non-spherical core-shell supramolecular aggregates with controlled dimensions, whereas the peptide amphiphile forms micrometer long nanofibers.